Categories of tropical forest types is difficult. While forests in temperate areas are readily categorised on the basis of tree canopy density, such schemes do not work well in tropical forests. There is no single scheme that defines what a forest is, in tropical regions or elsewhere. Because of these difficulties, information on the extent of tropical forests varies between sources. However Tropical Forests are extensive, making up just under half the world’s forests.
Tropical forests are often thought of as evergreen rainforests and moist forests, however in reality only up to 60% of tropical forest is rainforest (depending on how this is defined - see maps). The remaining tropical forests are a diversity of many different forest types including: seasonally-dry tropical forest, mangroves, tropical freshwater swamp forests (or "flooded forests" such as the Várzea of the Amazon), dry forest, open Eucalyptus forests, tropical coniferous forests, savanna woodland (e.g. Sahelian forest) and montane forests (the higher elevations of which are cloud forests). Over even relatively short distances, the boundaries between these biomes may be unclear, with ecotones between the main types.
The nature of tropical forest in any given area is affected by a number of factors, most importantly:
Extent of tropical and sub-tropical -